1. Field of the Invention
The present invention is directed to novel compositions, materials, methods of their use and methods of their manufacture that are generally useful as agents in the construction and building trades. More specifically, the compounds of the present invention can be used in construction and building applications that benefit from a relatively lightweight, extendable, moldable, pourable, material that has high strength and often improved insulation properties.
2. Description of the Prior Art
In the field of preparation and use of lightweight cementitious materials, such as so-called lightweight concrete, the materials that have been available to the trades up until now have generally required the addition of various constituents to achieve a strong but lightweight concrete mass that has a high homogeneity of constituents and which is uniformly bonded throughout the mass.
U.S. Pat. Nos. 3,214,393, 3,257,338 and 3,272,765 disclose concrete mixtures that contain cement, a primary aggregate, particulate expanded styrene polymer, and a homogenizing and/or a surface-active additive.
U.S. Pat. No. 3,021,291 discloses a method of making cellular concrete by incorporating into the concrete mixture, prior to casting the mixture, a polymeric material that will expand under the influence of heat during curing. The shape and size of the polymeric particles is not critical.
U.S. Pat. No. 5,580,378 discloses a lightweight cementitious product made up of an aqueous cementitious mixture that can include fly ash, Portland cement, sand, lime and, as a weight saving component, micronized polystyrene particles having particle sizes in the range of 50 to 2000 μm and a density of about 1 lb/ft3. The mixture can be poured into molded products such as foundation walls, roof tiles, bricks and the like. The product can also be used as a mason's mortar, a plaster, a stucco or a texture.
JP 9 071 449 discloses a lightweight concrete that includes Portland cement and a lightweight aggregate such as foamed polystyrene, perlite or vermiculite as a part or all parts of the aggregate. The foamed polystyrene has a granule diameter of 0.1-10 mm and a specific gravity of 0.01-0.08.
U.S. Pat. Nos. 5,580,378, 5,622,556, and 5,725,652 disclose lightweight cementitious products made up of an aqueous cementitious mixture that includes cement and expanded shale, clay, slate, fly ash, and/or lime, and a weight saving component, which is micronized polystyrene particles having particle sizes in the range of 50 to 2000 μm, and characterized by having water contents in the range of from about 0.5% to 50% v/v.
U.S. Pat. No. 4,265,964 discloses lightweight compositions for structural units such as wallboard panels and the like, which contain low density expandable thermoplastic granules; a cementitious base material, such as, gypsum; a surfactant; an additive which acts as a frothing agent to incorporate an appropriate amount of air into the mixture; a film forming component; and a starch. The expandable thermoplastic granules are expanded as fully as possible.
WO 98 02 397 discloses lightweight-concrete roofing tiles made by molding a hydraulic binder composition containing synthetic resin foams as the aggregate and having a specific gravity of about 1.6 to 2.
WO 00/61519 discloses a lightweight concrete that includes a blend of from around 40% to 99% of organic polymeric material and from 1% to around 60% of an air entraining agent. The blend is used for preparing lightweight concrete that uses polystyrene aggregate. The blend is required to disperse the polystyrene aggregate and to improve the bond between the polystyrene aggregate and surrounding cementitious binder.
WO 01/66485 discloses a lightweight cementitious mixture containing by volume: 5 to 80% cement, 10 to 65% expanded polystyrene particles; 10 to 90% expanded mineral particles; and water sufficient to make a paste with a substantially even distribution of expanded polystyrene after proper mixing.
U.S. Pat. No. 6,851,235 discloses a building block that includes a mixture of water, cement, and expanded polystyrene (EPS) foam beads that have a diameter from 3.18 mm (⅛ inch) to 9.53 mm (⅜ inch) in the proportions of from 68 to 95 liters (18 to 25 gallons) water; from 150 to 190 kg (325 to 425 lb) cement; and from 850 to 1400 liters (30 to 50 cubic feet) Prepuff beads.
Generally, the prior art recognizes the utility of using expanded polymers, in some form, in concrete compositions, to reduce the overall weight of the compositions. The expanded polymers are primarily added to take up space and create voids in the concrete and the amount of “air space” in the expanded polymer is typically maximized to achieve this objective. Generally, the prior art assumes that expanded polymer particles will lower the strength and/or structural integrity of lightweight concrete compositions. Further, concrete articles made from prior art lightweight concrete compositions have at best inconsistent physical properties, such as Young's modulus, thermal conductivity, and compressive strength, and typically demonstrate less than desirable physical properties.
Concrete walls in building construction are most often produced by first setting up two parallel form walls and pouring concrete into the space between the forms. After the concrete hardens, the builder then removes the forms, leaving the cured concrete wall.
This prior art technique has drawbacks. Formation of the concrete walls is inefficient because of the time required to erect the forms, wait until the concrete cures, and take down the forms. This prior art technique, therefore, is an expensive, labor-intensive process.
Accordingly, techniques have developed for forming modular concrete walls, which use a foam insulating material. The modular form walls are set up parallel to each other and connecting components hold the two form walls in place relative to each other while concrete is poured there between. The form walls, however, remain in place after the concrete cures. That is, the form walls, which are constructed of foam insulating material, are a permanent part of the building after the concrete cures. The concrete walls made using this technique can be stacked on top of each other many stories high to form all of a building's walls. In addition to the efficiency gained by retaining the form walls as part of the permanent structure, the materials of the form walls often provide adequate insulation for the building.
Although the prior art includes many proposed variations to achieve improvements with this technique, drawbacks still exist for each design. The connecting components used in the prior art to hold the walls are constructed of (1) plastic foam, (2) high density plastic, or (3) a metal bridge, which is a non-structural support, i.e., once the concrete cures, the connecting components serve no function. Even so, these members provide thermal and sound insulation functions and have long been accepted by the building industry.
Thus, current insulated concrete form technology requires the use of small molded foam blocks normally 12 to 24 inches in height with a standard length of four feet. The large amount of horizontal and vertical joints that require bracing to correctly position the blocks during a concrete pour, restricts their use to shorter wall lengths and lower wall heights. Wall penetrations such as windows and doors require skillfully prepared and engineered forming to withstand the pressures exerted upon them during concrete placement. Plaster finishing crews have difficulty hanging drywall on such systems due to the problem of locating molded in furring strips. The metal or plastic furring strips in current designs are non-continuous in nature and are normally embedded within the foam faces. The characteristics present in current block forming systems require skilled labor, long lay-out times, engineered blocking and shoring and non-traditional finishing skills. This results in a more expensive wall that is not suitable for larger wall construction applications. The highly skilled labor force that is required to place, block, shore and apply finishes in a block system seriously restricts the use of such systems when compared to traditional concrete construction techniques.
One approach to solving the problem of straight and true walls on larger layouts has been to design larger blocks. Current existing manufacturing technology has limited this increase to 24 inches in height and eight feet in length. Other systems create hot wire cut opposing foamed plastic panels mechanically linked together in a secondary operation utilizing metal or plastic connectors. These panels are normally 48 inches in width and 8 feet in height and do not contain continuous furring strips.
However, none of the approaches described above adequately address the problems of form blowout at higher wall heights due to pressure exerted by the poured concrete, fast and easy construction with an unskilled labor force, and ease of finishing the walls with readily ascertainable attachment points.
Therefore, there is a need in the art for lightweight concrete compositions that provide lightweight concrete articles having predictable and desirable physical properties as well as for composite pre-formed building panels and insulated concrete forms with internal blocking and bracing elements that overcome the above-described problems.